The European Union's three presidents have collected the Nobel peace prize in Oslo in recognition of six decades of work promoting "peace and reconciliation, democracy and human rights".

David Cameron was one of six EU leaders who decided not to attend. But his deputy, Nick Clegg, was there to represent the UK at the Nobel Institute.

Attendees heard the Nobel committee president, Thorbjoern Jagland, praise the EU's role in transforming a European "continent of war" into a "continent of peace".

"That should not be taken for granted – we have to struggle for it every day," he said.

Jagland told how the same prize had been awarded in the 1920s to the foreign ministers of France and Germany, marking post-first world war reconciliation. Then in the 1930s the continent had reverted to conflict and war. But, he said, now was the time to celebrate prolonged peace – and welcome the French and German leaders sitting side by side in Oslo.

The announcement of the peace award in October caused surprise and controversy in the midst of one of the EU's worst crises, and at a time of deep, albeit non-violent rifts between major member states.

The ceremony comes in the week of yet another EU summit to try to resolve the continuing eurozone crisis, which, according to the UK Independence party leader, Nigel Farage, risks "engendering violence, poverty and despair across Europe".

But the European commission president, José Manuel Barroso, said: "This is an award for the European project – for the people and the institutions – that day after day, for the last 60 years, have built a new Europe.

"We will honour this prize and we will preserve what has been achieved. It is in the common interest of our citizens. And it will allow Europe to contribute in shaping that 'better organised world' in line with the values of freedom, democracy, human rights and rule of law that we cherish and believe in.

"The last 60 years have shown that Europe can unite in peace. Over the next 60 years, Europe must lead the global quest for peace."

Receiving the award alongside him were the president of the European Council, Herman Van Rompuy, and the president of the European parliament, Martin Schulz.